This past week, baseball got a glimpse of the future as the Washington Nationals and Los Angeles Angels of Anaheim called up both Bryce Harper and Mike Trout respectively.

Big things are expected out of these two. Baseball America had Harper as the #1 prospect in all of baseball before this season, with Trout coming in at #3. The problem with rookies in fantasy baseball is you don’t have the luxury to wait around and see if they are good. If you are playing in a league that drafts yearly, you need production now. So will Harper, Trout and the rest of the top rookies make an impact? Let’s take a look.

Bryce Harper – Washington Nationals (OF)

If you are a baseball fan, you’ve known this kid since he was a high schooler. Remember, this is still a teenager playing a grown man’s game. As long as you don’t overpay for him, Harper can find a spot on any fantasy baseball team. The trouble will be getting him if you haven’t already. He has been snatched up in most leagues with heady owners. His average might not the greatest, but he’ll hit for power and steal some bases. Most importantly, the Nationals will give him the chance to succeed.

Matt Moore – Tampa Bay Rays (SP)

The world first found out about Matt Moore last year in the playoffs. The young left-hander dominated the Rangers in the ALDS by pitching seven scoreless innings. This is his first full year in the majors, and he has fit in nicely with the Rays. He is already owned in most leagues. Out of the four rookies, fantasy baseball owners should eye him the most. It also helps that he pitches on one of the best teams in baseball to rack up the wins.

Mike Trout – Los Angeles Angels of Anaheim (OF)

Before Harper came along, buzz surrounded Trout as the best position players in the minors. All around, he still might be. He can steal a base, has a little bit of pop and will probably get a chance to play every day. The best part is, only about half of the fantasy baseball teams out there have picked Trout up. If you need a spare outfielder, this guy can help you out.

Yu Darvish – Texas Rangers (SP)

So perhaps this 25-year old is not technically a rookie. He has played plenty of professional baseball over in Japan. A lot of hype came with the pitcher, and so far he has lived up to it. For fantasy baseball players, it’s not a matter of picking him up, it is if you should hold buy or sell him.

As good as Darvish has pitched, I’m a bit worried that the league will figure him out a little bit the 2nd time around. His numbers could very well level off around midseason. He also pitches in a hitter’s park, so that is something to remember. If you have him, trade him. If you want to have him, don’t trade for him unless you can get him for a steal.